Malt beverages which contain lower than traditional alcohol concentrations have been made and sold for many years. Recently there has been a renewed interest in such beverages and several major breweries have started to market such products.
Malt beverages, such as beer, containing lower amounts of alcohol may be made by modifying the fermentation process conditions to produce less alcohol or by using a carbohydrate source that will yield less alcohol. Alternatively, such beverages can be prepared by diluting the production of a conventional malt beverage fermentation with water to obtain the lower alcohol percentage or by removing the alcohol by evaporation or distillation.
None of the foregoing approaches is very satisfactory because they result in malt beverages that do not have the full flavor and consistency of the traditional malt beverages.
In British Pat. No. 1,447,505, a method of preparing a low alcohol beer is described which comprises using a reverse osmosis membrane to remove alcohol and water from a finished fermented beer. A number of membranes are described as being usable including aminated polyamid membranes, cellulose acetate membranes and nylon membranes. Attempts to prepare a low alcohol beer using the teachings and membranes of the aforementioned patent have not resulted in the preparation of low alcohol malt beverages of suitable or satisfactory flavor and composition.
Reverse osmosis has the advantages of speed of operation, mild operating conditions, and low operating costs compared to various other separation processes such as evaporation, dialysis, and the like. Such advantages are especially important where the material to be processed, such as malt beverages, is thermally unstable, or contains relatively large volumes of solvent to be processed.
It would be desirable to have a reverse osmosis method of preparing low alcohol malt beverages which contain the full flavor and consistency of traditional malt beverages.